The present invention relates to linear optical assemblies and, more particularly, to a linear optical assembly having a reduced size.
Linear optical assemblies are devices that convert narrow scan line portions of an image of an object to machine-readable image data, sometimes referred to herein simply as image data. Image data representing a larger portion of the object is generated by moving the linear optical assembly relative to the object as the linear optical assembly generates image data representative of successive scan line portions of the image of the object. The image data of the object is, accordingly, represented by a plurality of scan lines in a similar manner as a video display represents an image of an object. The process of generating image data representative of an image of an object is often referred to as imaging or scanning the object.
Linear optical assemblies are used in a wide variety of devices, such as optical scanning devices and facsimile machines. These devices are typically used to generate an image of printed material, such as text printed on a sheet of paper. The linear optical device or a peripheral processor is then able to replicate the image by processing the image data in a conventional manner. For example, a facsimile machine generates image data representative of text printed on a sheet of paper and transmits the image data via a telephone line to another facsimile machine that replicates the image of the text onto another sheet of paper. In another example, an optical scanning device generates image data representative of an object, such as text printed on a sheet of paper, and stores the image data for processing. The image data may, as an example, be used to alter the image of the object or to transfer an image of the object by electronic means, e.g., e-mail.
A linear optical assembly typically comprises a light-emitting device and a photodetecting device in addition to a plurality of various electronic components. The light-emitting device illuminates the object being imaged and the photodetecting device images the object. The electronic components serve to support the light-emitting device and the photodetecting device. The light-emitting device may, as an example, be a linear light source, such as a linear array of light-emitting diodes, sometimes referred to herein simply as LEDs. The photodetecting device typically consists of a linear array of photodetecting elements, sometimes referred to herein simply as photodetectors. The photodetectors are typically grouped in individual photodetector segments wherein each photodetector segment has a small linear array of photodetectors. The individual photodetector segments have a photodetecting portion and an interface portion, wherein the photodetecting portion has the linear array of photodetectors and the interface portion has a connector or the like to transmit data from the photodetectors. Accordingly, the photodetecting portion generates image data and the interface portion transmits the image data from the photodetector segment.
Some linear optical assemblies have the addition of two-dimensional photodetector arrays, sometimes referred to herein simply as navigators, that serve to determine the location of the linear optical assembly relative to the object being imaged as image data is being generated. In addition to the navigators, LEDs, and photodetecting device, the linear optical assembly may include several other electronic components that are required to operate the linear optical assembly. For example, electronic components are required to regulate voltages and to accommodate the flow of image data from the photodetectors.
In order to provide for ease of manufacture and reduced costs, the above-described components comprising the linear optical assembly are typically located on a single printed circuit board. The photodetector segments are arranged so they face the object being imaged. Additionally, the photodetector segments must be arranged so that the photodetecting portions are adjacent one another to form a continuous linear array of photodetectors. Likewise, the LEDs are positioned on the printed circuit board so as to illuminate the portion of the object being imaged by the photodetector segments.
It is generally desirable to reduce the sizes of the devices that use linear optical assemblies. For example, in the case of a facsimile machine, a smaller facsimile machine occupies less desk space, which is inherently beneficial. In the case of optical scanning devices, the use of small optical assemblies allows the optical scanning device to be portable.
Locating the components comprising the linear optical assembly on a single printed circuit board, however, tends to increase the size of the linear optical device. This is important due to the fact that the components comprising the linear optical device must be placed on the single printed circuit board so that they will not interfere with each other either optically or electrically. Furthermore, the photodetector segments must be linearly arranged and adjacent to each other. In the case of the LEDs, light emitted by the LEDs cannot intersect the navigators until the light has reflected from the object, otherwise the light will interfere with the light reflected from the object. Thus, the size of a linear optical assembly is generally limited by the physical and optical characteristics of the components comprising the linear optical assembly.
Accordingly, a need exists for a linear optical assembly having a reduced size wherein the components comprising the linear optical assembly are mounted to a single printed circuit board.
An optical assembly having a reduced size is disclosed herein. The optical assembly may comprise a printed circuit board having a plurality of electronic and optoelectronic components attached thereto. The optoelectronic components may include a linear arrangement of linear photosensor segments and at least one two-dimensional photosensing device. The electronic components may include a linear array of light-emitting diodes (LEDs) and other components necessary for the operation of the optoelectronic components. The components comprising the optical assembly may be electronically connected to a processor.
Each linear photosensor segment may have an interface portion and a photodetecting portion. The photodetecting portions may comprise linear arrays of photodetectors that convert portions of a scan line of an image of an object to image data. The interface portions may connect the photodetecting portions to the printed circuit board.
The photosensor segments may be arranged on the printed circuit board so that the photodetectors are linearly aligned along an axis. The interface portions of the individual photosensensor segments may face either a first direction or a second opposite direction. By orienting the interface portions in different directions, the photosensor segment may be arranged so as to best utilize the area of the printed circuit board. This in turn, allows for the optical assembly to have a reduced size. For example, the interface portions may be arranged so that they have spaces located therebetween. Other components comprising the optical assembly may be located in these spaces. Locating components in these spaces allows a high concentration of components to be located in the vicinity of the optical sensors rather than on other areas of the printed circuit board. This in turn, serves to reduce the area of the printed circuit board and, thus, the optical assembly.